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PERLGIT(1)              Perl Programmers Reference Guide             PERLGIT(1)

NAME
       perlgit - Detailed information about git and the Perl repository

DESCRIPTION
       This document provides details on using git to develop Perl. If you are
       just interested in working on a quick patch, see perlhack first.  This
       document is intended for people who are regular contributors to Perl,
       including those with write access to the git repository.

CLONING THE REPOSITORY
       All of Perl's source code is kept centrally in a Git repository at
       github.com.

       You can make a read-only clone of the repository by running:

         % git clone git@github.com:Perl/perl5.git perl

       If you cannot use that for firewall reasons, you can also clone via
       http:

         % git clone https://github.com/Perl/perl5.git perl

WORKING WITH THE REPOSITORY
       Once you have changed into the repository directory, you can inspect it.
       After a clone the repository will contain a single local branch, which
       will be the current branch as well, as indicated by the asterisk.

         % git branch
         * blead

       Using the -a switch to "branch" will also show the remote tracking
       branches in the repository:

         % git branch -a
         * blead
           origin/HEAD
           origin/blead
         ...

       The branches that begin with "origin" correspond to the "git remote"
       that you cloned from (which is named "origin"). Each branch on the
       remote will be exactly tracked by these branches. You should NEVER do
       work on these remote tracking branches. You only ever do work in a local
       branch. Local branches can be configured to automerge (on pull) from a
       designated remote tracking branch. This is the case with the default
       branch "blead" which will be configured to merge from the remote
       tracking branch "origin/blead".

       You can see recent commits:

         % git log

       And pull new changes from the repository, and update your local
       repository (must be clean first)

         % git pull

       Assuming we are on the branch "blead" immediately after a pull, this
       command would be more or less equivalent to:

         % git fetch
         % git merge origin/blead

       In fact if you want to update your local repository without touching
       your working directory you do:

         % git fetch

       And if you want to update your remote-tracking branches for all defined
       remotes simultaneously you can do

         % git remote update

       Neither of these last two commands will update your working directory,
       however both will update the remote-tracking branches in your
       repository.

       To make a local branch of a remote branch:

         % git checkout -b maint-5.10 origin/maint-5.10

       To switch back to blead:

         % git checkout blead

   Finding out your status
       The most common git command you will use will probably be

         % git status

       This command will produce as output a description of the current state
       of the repository, including modified files and unignored untracked
       files, and in addition it will show things like what files have been
       staged for the next commit, and usually some useful information about
       how to change things. For instance the following:

        % git status
        On branch blead
        Your branch is ahead of 'origin/blead' by 1 commit.

        Changes to be committed:
          (use "git reset HEAD <file>..." to unstage)

              modified:   pod/perlgit.pod

        Changes not staged for commit:
          (use "git add <file>..." to update what will be committed)
          (use "git checkout -- <file>..." to discard changes in working
                                                                     directory)

              modified:   pod/perlgit.pod

        Untracked files:
          (use "git add <file>..." to include in what will be committed)

              deliberate.untracked

       This shows that there were changes to this document staged for commit,
       and that there were further changes in the working directory not yet
       staged. It also shows that there was an untracked file in the working
       directory, and as you can see shows how to change all of this. It also
       shows that there is one commit on the working branch "blead" which has
       not been pushed to the "origin" remote yet. NOTE: This output is also
       what you see as a template if you do not provide a message to "git
       commit".

   Patch workflow
       First, please read perlhack for details on hacking the Perl core.  That
       document covers many details on how to create a good patch.

       If you already have a Perl repository, you should ensure that you're on
       the blead branch, and your repository is up to date:

         % git checkout blead
         % git pull

       It's preferable to patch against the latest blead version, since this is
       where new development occurs for all changes other than critical bug
       fixes. Critical bug fix patches should be made against the relevant
       maint branches, or should be submitted with a note indicating all the
       branches where the fix should be applied.

       Now that we have everything up to date, we need to create a temporary
       new branch for these changes and switch into it:

         % git checkout -b orange

       which is the short form of

         % git branch orange
         % git checkout orange

       Creating a topic branch makes it easier for the maintainers to rebase or
       merge back into the master blead for a more linear history. If you don't
       work on a topic branch the maintainer has to manually cherry pick your
       changes onto blead before they can be applied.

       That'll get you scolded on perl5-porters, so don't do that. Be Awesome.

       Then make your changes. For example, if Leon Brocard changes his name to
       Orange Brocard, we should change his name in the AUTHORS file:

         % perl -pi -e 's{Leon Brocard}{Orange Brocard}' AUTHORS

       You can see what files are changed:

         % git status
         On branch orange
         Changes to be committed:
           (use "git reset HEAD <file>..." to unstage)

            modified:   AUTHORS

       And you can see the changes:

        % git diff
        diff --git a/AUTHORS b/AUTHORS
        index 293dd70..722c93e 100644
        --- a/AUTHORS
        +++ b/AUTHORS
        @@ -541,7 +541,7 @@    Lars Hecking              <lhecking@nmrc.ucc.ie>
         Laszlo Molnar                  <laszlo.molnar@eth.ericsson.se>
         Leif Huhn                      <leif@hale.dkstat.com>
         Len Johnson                    <lenjay@ibm.net>
        -Leon Brocard                   <acme@astray.com>
        +Orange Brocard                 <acme@astray.com>
         Les Peters                     <lpeters@aol.net>
         Lesley Binks                   <lesley.binks@gmail.com>
         Lincoln D. Stein               <lstein@cshl.org>

       Now commit your change locally:

        % git commit -a -m 'Rename Leon Brocard to Orange Brocard'
        Created commit 6196c1d: Rename Leon Brocard to Orange Brocard
         1 files changed, 1 insertions(+), 1 deletions(-)

       The "-a" option is used to include all files that git tracks that you
       have changed. If at this time, you only want to commit some of the files
       you have worked on, you can omit the "-a" and use the command
       "git add FILE ..." before doing the commit. "git add --interactive"
       allows you to even just commit portions of files instead of all the
       changes in them.

       The "-m" option is used to specify the commit message. If you omit it,
       git will open a text editor for you to compose the message
       interactively. This is useful when the changes are more complex than the
       sample given here, and, depending on the editor, to know that the first
       line of the commit message doesn't exceed the 50 character legal
       maximum. See "Commit message" in perlhack for more information about
       what makes a good commit message.

       Once you've finished writing your commit message and exited your editor,
       git will write your change to disk and tell you something like this:

        Created commit daf8e63: explain git status and stuff about remotes
         1 files changed, 83 insertions(+), 3 deletions(-)

       If you re-run "git status", you should see something like this:

        % git status
        On branch orange
        Untracked files:
          (use "git add <file>..." to include in what will be committed)

              deliberate.untracked

        nothing added to commit but untracked files present (use "git add" to
                                                                         track)

       When in doubt, before you do anything else, check your status and read
       it carefully, many questions are answered directly by the git status
       output.

       You can examine your last commit with:

         % git show HEAD

       and if you are not happy with either the description or the patch itself
       you can fix it up by editing the files once more and then issue:

         % git commit -a --amend

       Now, create a fork on GitHub to push your branch to, and add it as a
       remote if you haven't already, as described in the GitHub documentation
       at <https://help.github.com/en/articles/working-with-forks>:

         % git remote add fork git@github.com:MyUser/perl5.git

       And push the branch to your fork:

         % git push -u fork orange

       You should now submit a Pull Request (PR) on GitHub from the new branch
       to blead. For more information, see the GitHub documentation at
       <https://help.github.com/en/articles/creating-a-pull-request-from-a-fork>.

       You can also send patch files to perl5-porters@perl.org
       <mailto:perl5-porters@perl.org> directly if the patch is not ready to be
       applied, but intended for discussion.

       To create a patch file for all your local changes:

         % git format-patch -M blead..
         0001-Rename-Leon-Brocard-to-Orange-Brocard.patch

       Or for a lot of changes, e.g. from a topic branch:

         % git format-patch --stdout -M blead.. > topic-branch-changes.patch

       If you want to delete your temporary branch, you may do so with:

        % git checkout blead
        % git branch -d orange
        error: The branch 'orange' is not an ancestor of your current HEAD.
        If you are sure you want to delete it, run 'git branch -D orange'.
        % git branch -D orange
        Deleted branch orange.

   A note on derived files
       Be aware that many files in the distribution are derivative--avoid
       patching them, because git won't see the changes to them, and the build
       process will overwrite them. Patch the originals instead. Most utilities
       (like perldoc) are in this category, i.e. patch utils/perldoc.PL rather
       than utils/perldoc. Similarly, don't create patches for files under
       $src_root/ext from their copies found in $install_root/lib. If you are
       unsure about the proper location of a file that may have gotten copied
       while building the source distribution, consult the MANIFEST.

   Cleaning a working directory
       The command "git clean" can with varying arguments be used as a
       replacement for "make clean".

       To reset your working directory to a pristine condition you can do:

         % git clean -dxf

       However, be aware this will delete ALL untracked content. You can use

         % git clean -Xf

       to remove all ignored untracked files, such as build and test byproduct,
       but leave any manually created files alone.

       If you only want to cancel some uncommitted edits, you can use "git
       checkout" and give it a list of files to be reverted, or "git checkout
       -f" to revert them all.

       If you want to cancel one or several commits, you can use "git reset".

   Bisecting
       "git" provides a built-in way to determine which commit should be blamed
       for introducing a given bug. "git bisect" performs a binary search of
       history to locate the first failing commit. It is fast, powerful and
       flexible, but requires some setup and to automate the process an
       auxiliary shell script is needed.

       The core provides a wrapper program, Porting/bisect.pl, which attempts
       to simplify as much as possible, making bisecting as simple as running a
       Perl one-liner. For example, if you want to know when this became an
       error:

           perl -e 'my $x := 2'

       you simply run this:

           .../Porting/bisect.pl -e 'my $x := 2;'

       Using Porting/bisect.pl, with one command (and no other files) it's easy
       to find out

       •   Which commit caused this example code to break?

       •   Which commit caused this example code to start working?

       •   Which commit added the first file to match this regex?

       •   Which commit removed the last file to match this regex?

       usually  without  needing to know which versions of perl to use as start
       and end revisions, as Porting/bisect.pl automatically searches  to  find
       the  earliest  stable  version  for  which  the  test  case  passes. Run
       "Porting/bisect.pl --help" for the full documentation, including how  to
       set the "Configure" and build time options.

       If  you  require  more  flexibility than Porting/bisect.pl has to offer,
       you'll need to run "git bisect" yourself. It's most useful to  use  "git
       bisect  run" to automate the building and testing of perl revisions. For
       this you'll need a shell script for "git" to call to test  a  particular
       revision.  An  example  script  is  Porting/bisect-example.sh, which you
       should copy outside of the repository, as the bisect process will  reset
       the  state to a clean checkout as it runs. The instructions below assume
       that you copied it as ~/run and then edited it as appropriate.

       You first enter in bisect mode with:

         % git bisect start

       For example, if the bug is present on "HEAD" but wasn't in 5.10.0, "git"
       will learn about this when you enter:

         % git bisect bad
         % git bisect good perl-5.10.0
         Bisecting: 853 revisions left to test after this

       This results in checking  out  the  median  commit  between  "HEAD"  and
       "perl-5.10.0". You can then run the bisecting process with:

         % git bisect run ~/run

       When the first bad commit is isolated, "git bisect" will tell you so:

         ca4cfd28534303b82a216cfe83a1c80cbc3b9dc5 is first bad commit
         commit ca4cfd28534303b82a216cfe83a1c80cbc3b9dc5
         Author: Dave Mitchell <davem@fdisolutions.com>
         Date:   Sat Feb 9 14:56:23 2008 +0000

             [perl #49472] Attributes + Unknown Error
             ...

         bisect run success

       You  can  peek into the bisecting process with "git bisect log" and "git
       bisect visualize". "git bisect reset" will get you out of bisect mode.

       Please note that the first "good" state must be an ancestor of the first
       "bad" state. If you want to search for the commit that solved some  bug,
       you  have to negate your test case (i.e. exit with 1 if OK and 0 if not)
       and still mark the lower bound as "good" and the  upper  as  "bad".  The
       "first  bad commit" has then to be understood as the "first commit where
       the bug is solved".

       "git help bisect" has much more information on how you  can  tweak  your
       binary searches.

       Following  bisection  you  may wish to configure, build and test perl at
       commits identified by the bisection  process.   Sometimes,  particularly
       with older perls, "make" may fail during this process.  In this case you
       may  be  able to patch the source code at the older commit point.  To do
       so, please follow the suggestions provided in "Building  perl  at  older
       commits" in perlhack.

   Topic branches and rewriting history
       Individual    committers    should    create    topic   branches   under
       yourname/some_descriptive_name:

         % branch="$yourname/$some_descriptive_name"
         % git checkout -b $branch
         ... do local edits, commits etc ...
         % git push origin -u $branch

       Should you be stuck with an ancient version of git (prior to 1.7),  then
       "git  push"  will  not have the "-u" switch, and you have to replace the
       last step with the following sequence:

         % git push origin $branch:refs/heads/$branch
         % git config branch.$branch.remote origin
         % git config branch.$branch.merge refs/heads/$branch

       If you want to make changes to someone else's topic branch,  you  should
       check with its creator before making any change to it.

       You  might  sometimes  find  that  the  original  author  has edited the
       branch's history. There are lots of good reasons for this. Sometimes, an
       author might simply be rebasing the branch onto a  newer  source  point.
       Sometimes,  an author might have found an error in an early commit which
       they wanted to fix before merging the branch to blead.

       Currently the master repository is configured to forbid non-fast-forward
       merges. This means that the branches  within  can  not  be  rebased  and
       pushed as a single step.

       The only way you will ever be allowed to rebase or modify the history of
       a  pushed  branch  is to delete it and push it as a new branch under the
       same name. Please think carefully about doing this. It may be better  to
       sequentially  rename  your  branches  so  that  it  is easier for others
       working with you  to  cherry-pick  their  local  changes  onto  the  new
       version. (XXX: needs explanation).

       If  you  want to rebase a personal topic branch, you will have to delete
       your existing topic branch and push as a new version of it. You  can  do
       this via the following formula (see the explanation about "refspec"'s in
       the  git  push  documentation  for  details) after you have rebased your
       branch:

         # first rebase
         % git checkout $user/$topic
         % git fetch
         % git rebase origin/blead

         # then "delete-and-push"
         % git push origin :$user/$topic
         % git push origin $user/$topic

       NOTE: it is forbidden at the repository  level  to  delete  any  of  the
       "primary"      branches.     That     is     any     branch     matching
       "m!^(blead|maint|perl)!". Any attempt  to  do  so  will  result  in  git
       producing an error like this:

         % git push origin :blead
         *** It is forbidden to delete blead/maint branches in this repository
         error: hooks/update exited with error code 1
         error: hook declined to update refs/heads/blead
         To ssh://perl5.git.perl.org/perl
          ! [remote rejected] blead (hook declined)
          error: failed to push some refs to 'ssh://perl5.git.perl.org/perl'

       As  a  matter  of  policy  we  do  not edit the history of the blead and
       maint-* branches. If a typo (or worse) sneaks into a commit to blead  or
       maint-*,  we'll  fix  it  in  another  commit. The only types of updates
       allowed on these branches are  "fast-forwards",  where  all  history  is
       preserved.

       Annotated  tags  in  the  canonical  perl.git  repository  will never be
       deleted or modified. Think long and hard about whether you want to  push
       a  local  tag  to  perl.git before doing so. (Pushing simple tags is not
       allowed.)

   Grafts
       The perl history contains one  mistake  which  was  not  caught  in  the
       conversion:  a  merge  was  recorded  in  the  history between blead and
       maint-5.10 where no merge actually occurred. Due to the nature  of  git,
       this  is  now impossible to fix in the public repository. You can remove
       this  mis-merge  locally  by  adding  the   following   line   to   your
       ".git/info/grafts" file:

        296f12bbbbaa06de9be9d09d3dcf8f4528898a49 434946e0cb7a32589ed92d18008aaa1d88515930

       It is particularly important to have this graft line if any bisecting is
       done in the area of the "merge" in question.

WRITE ACCESS TO THE GIT REPOSITORY
       Once  you  have  write  access,  you will need to modify the URL for the
       origin remote to enable pushing. Edit .git/config with the git-config(1)
       command:

         % git config remote.origin.url git@github.com:Perl/perl5.git

       You can also set up your user name and e-mail address.  Most  people  do
       this once globally in their ~/.gitconfig by doing something like:

         % git config --global user.name "Ævar Arnfjörð Bjarmason"
         % git config --global user.email avarab@gmail.com

       However, if you'd like to override that just for perl, execute something
       like the following in perl:

         % git config user.email avar@cpan.org

       It  is  also  possible  to  keep "origin" as a git remote, and add a new
       remote for ssh access:

         % git remote add camel git@github.com:Perl/perl5.git

       This allows  you  to  update  your  local  repository  by  pulling  from
       "origin",  which  is faster and doesn't require you to authenticate, and
       to push your changes back with the "camel" remote:

         % git fetch camel
         % git push camel

       The "fetch" command just  updates  the  "camel"  refs,  as  the  objects
       themselves should have been fetched when pulling from "origin".

   Working with Github pull requests
       Pull  requests  typically  originate from outside of the "Perl/perl.git"
       repository, so if you want to test or work with  it  locally  a  vanilla
       "git fetch" from the "Perl/perl5.git" repository won't fetch it.

       However  Github  does  provide  a mechanism to fetch a pull request to a
       local branch.  They are available on Github remotes  under  "pull/",  so
       you  can  use "git fetch pull/PRID/head:localname" to make a local copy.
       eg.  to fetch pull request 9999 to the local branch  "local-branch-name"
       run:

         git fetch origin pull/9999/head:local-branch-name

       and then:

         git checkout local-branch-name

       Note:  this branch is not rebased on "blead", so instead of the checkout
       above, you might want:

         git rebase origin/blead local-branch-name

       which rebases "local-branch-name" on "blead", and checks it out.

       Alternatively you can configure the remote to fetch all pull requests as
       remote-tracking branches.  To do this edit the  remote  in  .git/config,
       for example if your github remote is "origin" you'd have:

         [remote "origin"]
                 url = git@github.com:/Perl/perl5.git
                 fetch = +refs/heads/*:refs/remotes/origin/*

       Add  a  line  to map the remote pull request branches to remote-tracking
       branches:

         [remote "origin"]
                 url = git@github.com:/Perl/perl5.git
                 fetch = +refs/heads/*:refs/remotes/origin/*
                 fetch = +refs/pull/*/head:refs/remotes/origin/pull/*

       and then do a fetch as normal:

         git fetch origin

       This will create  a  remote-tracking  branch  for  every  pull  request,
       including closed requests.

       To  remove  those  remote-tracking branches, remove the line added above
       and prune:

         git fetch -p origin # or git remote prune origin

   Accepting a patch
       If you have received a patch file generated using the above section, you
       should try out the patch.

       First we need to create a temporary new branch  for  these  changes  and
       switch into it:

        % git checkout -b experimental

       Patches  that were formatted by "git format-patch" are applied with "git
       am":

        % git am 0001-Rename-Leon-Brocard-to-Orange-Brocard.patch
        Applying Rename Leon Brocard to Orange Brocard

       Note that  some  UNIX  mail  systems  can  mess  with  text  attachments
       containing 'From '. This will fix them up:

        % perl -pi -e's/^>From /From /' \
                               0001-Rename-Leon-Brocard-to-Orange-Brocard.patch

       If  just  a  raw diff is provided, it is also possible use this two-step
       process:

        % git apply bugfix.diff
        % git commit -a -m "Some fixing" \
                                   --author="That Guy <that.guy@internets.com>"

       Now we can inspect the change:

        % git show HEAD
        commit b1b3dab48344cff6de4087efca3dbd63548ab5e2
        Author: Leon Brocard <acme@astray.com>
        Date:   Fri Dec 19 17:02:59 2008 +0000

          Rename Leon Brocard to Orange Brocard

        diff --git a/AUTHORS b/AUTHORS
        index 293dd70..722c93e 100644
        --- a/AUTHORS
        +++ b/AUTHORS
        @@ -541,7 +541,7 @@ Lars Hecking                 <lhecking@nmrc.ucc.ie>
         Laszlo Molnar                  <laszlo.molnar@eth.ericsson.se>
         Leif Huhn                      <leif@hale.dkstat.com>
         Len Johnson                    <lenjay@ibm.net>
        -Leon Brocard                   <acme@astray.com>
        +Orange Brocard                 <acme@astray.com>
         Les Peters                     <lpeters@aol.net>
         Lesley Binks                   <lesley.binks@gmail.com>
         Lincoln D. Stein               <lstein@cshl.org>

       If you are a committer to Perl and you think the patch is good, you  can
       then merge it into blead then push it out to the main repository:

         % git checkout blead
         % git merge experimental
         % git push origin blead

       If you want to delete your temporary branch, you may do so with:

        % git checkout blead
        % git branch -d experimental
        error: The branch 'experimental' is not an ancestor of your current
        HEAD.  If you are sure you want to delete it, run 'git branch -D
        experimental'.
        % git branch -D experimental
        Deleted branch experimental.

   Committing to blead
       The 'blead' branch will become the next production release of Perl.

       Before pushing any local change to blead, it's incredibly important that
       you  do  a  few  things,  lest  other  committers  come  after  you with
       pitchforks and torches:

       •   Make sure you have a good commit message. See  "Commit  message"  in
           perlhack for details.

       •   Run  the  test  suite.  You  might not think that one typo fix would
           break a test file. You'd be wrong. Here's an example  of  where  not
           running  the suite caused problems. A patch was submitted that added
           a couple of tests to an existing .t.  It  couldn't  possibly  affect
           anything  else,  so  no  need to test beyond the single affected .t,
           right?  But, the submitter's email address  had  changed  since  the
           last  of  their  submissions,  and  this caused other tests to fail.
           Running the test target given in the next  item  would  have  caught
           this problem.

       •   If  you don't run the full test suite, at least "make test_porting".
           This will run basic sanity checks. To see which sanity checks,  have
           a look in t/porting.

       •   If  you  make any changes that affect miniperl or core routines that
           have different code  paths  for  miniperl,  be  sure  to  run  "make
           minitest".   This  will catch problems that even the full test suite
           will not catch because it runs a  subset  of  tests  under  miniperl
           rather than perl.

   On merging and rebasing
       Simple,  one-off  commits  pushed to the 'blead' branch should be simple
       commits that apply cleanly.  In other words, you should make  sure  your
       work is committed against the current position of blead, so that you can
       push back to the master repository without merging.

       Sometimes,  blead  will  move  while  you're  building  or  testing your
       changes.  When this happens, your push will be rejected with  a  message
       like this:

        To ssh://perl5.git.perl.org/perl.git
         ! [rejected]        blead -> blead (non-fast-forward)
        error: failed to push some refs to 'ssh://perl5.git.perl.org/perl.git'
        To prevent you from losing history, non-fast-forward updates were
        rejected Merge the remote changes (e.g. 'git pull') before pushing
        again.  See the 'Note about fast-forwards' section of 'git push --help'
        for details.

       When  this  happens,  you  can  just  rebase  your  work against the new
       position of blead, like  this  (assuming  your  remote  for  the  master
       repository is "p5p"):

         % git fetch p5p
         % git rebase p5p/blead

       You will see your commits being re-applied, and you will then be able to
       push  safely.   More  information  about  rebasing  can  be found in the
       documentation for the git-rebase(1) command.

       For larger sets of commits that only make sense together, or that  would
       benefit  from  a  summary  of  the set's purpose, you should use a merge
       commit.  You should perform your work  on  a  topic  branch,  which  you
       should  regularly  rebase  against blead to ensure that your code is not
       broken by blead moving.   When  you  have  finished  your  work,  please
       perform  a final rebase and test.  Linear history is something that gets
       lost with every commit on blead, but a final rebase  makes  the  history
       linear  again,  making  it easier for future maintainers to see what has
       happened.  Rebase as follows (assuming  your  work  was  on  the  branch
       "committer/somework"):

         % git checkout committer/somework
         % git rebase blead

       Then you can merge it into master like this:

         % git checkout blead
         % git merge --no-ff --no-commit committer/somework
         % git commit -a

       The  switches  above deserve explanation.  "--no-ff" indicates that even
       if all your work can be applied linearly against blead, a  merge  commit
       should still be prepared.  This ensures that all your work will be shown
       as  a side branch, with all its commits merged into the mainstream blead
       by the merge commit.

       "--no-commit" means that the merge  commit  will  be  prepared  but  not
       committed.   The commit is then actually performed when you run the next
       command, which will  bring  up  your  editor  to  describe  the  commit.
       Without  "--no-commit",  the  commit would be made with nearly no useful
       message, which would greatly diminish the value of the merge commit as a
       placeholder for the work's description.

       When describing the merge commit, explain the purpose of the branch, and
       keep in mind that this description will probably be used by the eventual
       release engineer when reviewing the next perldelta document.

       If the subsequent push fails then you must be careful on how you rebase.
       If you use

         % git rebase p5p/blead

       or

         % git pull --rebase

       then your carefully created merge commit will be lost! To avoid this you
       can use:

         % git fetch p5p
         % git rebase --rebase-merges p5p/blead

       This will recreate your merge commit.

       (Should you be stuck with an older version of git (prior to 2.18),  then
       "git  rebase"  will  not  have the "--rebase-merges" switch, instead you
       have to use the "--preserve-merges" switch.)

   Committing to maintenance versions
       Maintenance versions should only be altered to add critical  bug  fixes,
       see perlpolicy.

       To  commit  to a maintenance version of perl, you need to create a local
       tracking branch:

         % git checkout --track -b maint-5.005 origin/maint-5.005

       This creates a local branch named "maint-5.005", which tracks the remote
       branch "origin/maint-5.005". Then you can pull, commit, merge  and  push
       as before.

       You can also cherry-pick commits from blead and another branch, by using
       the "git cherry-pick" command. It is recommended to use the -x option to
       "git  cherry-pick" in order to record the SHA1 of the original commit in
       the new commit message.

       Before pushing any change to a maint version, make sure you've satisfied
       the steps in "Committing to blead" above.

   Using a smoke-me branch to test changes
       Sometimes a change affects code paths which you cannot test on the  OSes
       which  are  directly available to you and it would be wise to have users
       on other OSes test the change before you commit it to blead.

       Fortunately, there is a way to get your change smoke-tested  on  various
       OSes:  push  it  to  a  "smoke-me" branch and wait for certain automated
       smoke-testers to report the  results  from  their  OSes.   A  "smoke-me"
       branch  is  identified  by  the  branch  name:  specifically, as seen on
       github.com it must be a local  branch  whose  first  name  component  is
       precisely "smoke-me".

       The procedure for doing this is roughly as follows (using the example of
       tonyc's smoke-me branch called win32stat):

       First, make a local branch and switch to it:

         % git checkout -b win32stat

       Make some changes, build perl and test your changes, then commit them to
       your  local  branch.  Then  push  your local branch to a remote smoke-me
       branch:

         % git push origin win32stat:smoke-me/tonyc/win32stat

       Now you can switch back to blead locally:

         % git checkout blead

       and continue working on other things  while  you  wait  a  day  or  two,
       keeping  an  eye  on  the results reported for your "smoke-me" branch at
       <https://perl.develop-help.com/?b=smoke-me/tonyc/win32state>.

       If all is well then update your blead branch:

         % git pull

       then checkout your smoke-me branch once more and rebase it on blead:

         % git rebase blead win32stat

       Now switch back to blead and merge your smoke-me branch into it:

         % git checkout blead
         % git merge win32stat

       As described earlier, if there are many changes on your smoke-me  branch
       then  you  should prepare a merge commit in which to give an overview of
       those changes by using the following command instead of the last command
       above:

         % git merge win32stat --no-ff --no-commit

       You should now build perl and test your (merged) changes one  last  time
       (ideally  run  the  whole  test suite, but failing that at least run the
       t/porting/*.t tests) before pushing your changes as usual:

         % git push origin blead

       Finally, you should then delete the remote smoke-me branch:

         % git push origin :smoke-me/tonyc/win32stat

       (which is likely to produce a warning like this, which can be ignored:

        remote: fatal: ambiguous argument
                                         'refs/heads/smoke-me/tonyc/win32stat':
        unknown revision or path not in the working tree.
        remote: Use '--' to separate paths from revisions

       ) and then delete your local branch:

         % git branch -d win32stat

perl v5.40.1                       2026-08-30                        PERLGIT(1)

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